BSP reconstructions also suggest slight differences in times of coalescence and demographic events for each Microdipodops clade (Fig. 4). In combination with the other assessments of historical demography, there are strong indications of past population expansions for the M. megacephalus eastern and central clades and both of the M. pallidus clades. Population expansion is rejected in the M. megacephalus western clade based on the mismatch SSD, but a nonsignificant raggedness index and a negative (albeit nonsignificant) Fu’s FS indicates expansion (Table 3). This discrepancy suggests that members of this clade underwent a complex demographic history (i.e., recent bottleneck, migration, or population subdivision). Given unique geographical distributions, as well as the likelihood that each clade
represents a cryptic species, differences are not unexpected. Variation among estimates of genetic diversity may explain
observed differences in times of coalescence; clades withinM. megacephalus show generally higher values of nucleotide
diversity and longer times to coalescence than the M.pallidus clades (Table 3; Fig. 4). Despite distinct differences
in geographic distributions and genetic diversity, population sizes do not appear to vary drastically among the clades
(Fig. 4), with differences in demographic histories occurring largely within the past 200,000 years.